Raxacoricofallapatorians hatched from large, green eggs with several tendrils. (TV: Boom Town) By the age of twelve, Raxacoricofallapatorians were still considered children and were shorter than a human of equivalent age. (TV: Revenge of the Slitheen) As Raxacoricofallapatorians aged, they lost moisture from their tissue, calcifying and effectively turning into stone. (PROSE: The Slitheen Excursion)

Despite their large bulk, they were also capable of surprising speeds and could easily overpower a human. Raxacoricofallapatorians could hunt by scent and could identify an individual's species, age, sex, emotional state and location by it. This sense of smell was officially the best in the galaxy. (TV: Revenge of the Slitheen) They could also sense the pain of closely related individuals from far away. (TV: Aliens of London/World War Three)

Raxacoricofallapatorians had a more efficient metabolism than a human, meaning they only needed to eat every few weeks and produced less waste. Raxacoricofallapatorian blood was red and their tears were milky in colour and slightly acidic. (PROSE: The Monsters Inside) The females of the species could create poison when in danger, released either by a dart-like claw or through their breath. (TV: Boom Town) This breath could render a human unconscious. (COMIC: Doctormania)

Unlike the Slitheen and Blathereen families most Raxacoricofallapatorians were a peaceful race that taught their children maths and poetry. they made their home world a paradise for them and other peace loving species and some of them were brilliant farmers but they despise criminal members of their species and punish them without mercy.

The Raxacoricofallapatorians had the death sentence for dangerous criminals like the Slitheens, which was carried out in a gruesome way. The criminal would be lowered into a cauldron of acetic acid, which would then be heated to boiling. The acidity of the solution was formulated to dissolve the skin, allowing the internal organs to drop into the liquid while the condemned was still alive, resulting in a slow and painful death. (TV: Boom Town)

Based on the comments of Blon, Raxacoricofallapatorians neither brushed their teeth nor prepared their food in complicated ways. (TV: Boom Town)

Two known Raxacoricofallapatorians insults were "May plaque brown your belly" and "May your mother boil in the cauldron of atonement". Both were presumably related to their calcium based biology. (PROSE: The Monsters Inside)

In an alternate timeline the Cybermen, using Borg technology conquered Raxacoricofallapatorius and converted the entire populace into Cybermen. (COMIC: Assimilation²)

In a timeline created by a continuity bomb where the Doctor embraced the title of "Time Lord Victorious" and became a mad tyrant who ruled over time and space, a Raxacoricofallapatorian shot him dead without regeneration. (COMIC: Four Doctors)

In the Shadow Proclamation scene in The Stolen Earth, Raxacoricofallapatorians were originally going to appear along with a child version of Blon. Strangely, the sketch depicted them as having four fingers rather than three as seen on TV. (REF: Doctor Who: The Writer's Tale)

The non-narrative source Doctor Who: The Visual Dictionary gave further information about Raxacoricofallapatorian biology and culture. It said they were well adapted to their home-planet, with large eyes to see through the blizzards of the poles and powerful arms to swim through the oceans and to hatch from their eggs. While hunting, they would use their strength and poison-tipped claws to kill their prey.